Correction to: Vascular endothelial growth factor is an autocrine growth factor, signaling through neuropilin-1 in non-small cell lung cancer.

Since the publication of this work [1] and in response to a recent query that was brought to our attention in relation to the Western Blot in Figure 1(C) for NP2, protein lysates prepared around the same time as those presented in the manuscript in question, were run by SDS-PAGE under similar experimental conditions and probed using the same primary antibodies to NP1 and NP2 that were used originally.

Visceral Adipose Tissue Modulates Radiosensitivity in Oesophageal Adenocarcinoma.

Oesophageal adenocarcinoma (OAC) is an exemplar model of obesity-associated cancer. Response to neoadjuvant chemoradiotherapy (NA CRT) is a clinical challenge. We examined if visceral adipose tissue and obesity status alter radiosensitivity in OAC. The radioresistant (OE33R) and radioresponsive (OE33P) OAC isogenic model was cultured with adipose tissue conditioned media from three patient cohorts: non-cancer patients, surgery only OAC patients and NA CRT OAC patients. Cell survival was characterised by clonogenic assay, metabolomic profiling by nuclear magnetic resonance spectroscopy and adipokine receptor gene expression by qPCR. A retrospective in vivo study compared tumour response to NA CRT in normal weight (n=53) versus overweight/obese patients (n=148). Adipose conditioned media (ACM) from all patient cohorts significantly increased radiosensitivity in radioresistant OE33R cells. ACM from the NA CRT OAC cohort increased radiosensitivity in OE33P cells. Metabolomic profiling demonstrated separation of the non-cancer and surgery only OAC cohorts and between the non-cancer and NA CRT OAC cohorts. Gene expression profiling of OE33P versus OE33R cells demonstrated differential expression of the adiponectin receptor-1 (AR1), adiponectin receptor-2 (AR2), leptin receptor (LepR) and neuropilin receptor-1 (NRP1) genes. In vivo overweight/obese OAC patients achieved an enhanced tumour response following NA CRT compared to normal weight patients. This study demonstrates that visceral adipose tissue modulates the cellular response to radiation in OAC.

The next generation of PI3K-Akt-mTOR pathway inhibitors in breast cancer cohorts.

The PI3K/Akt/mTOR pathway plays a role in various oncogenic processes in breast cancer and key pathway aberrations have been identified which drive the different molecular subtypes. Early drugs developed targeting this pathway produced some clinical success but were hampered by pharmacokinetics, tolerability and efficacy problems. This created a need for new PI3K pathway-inhibiting drugs, which would produce more robust results allowing incorporation into treatment regimens for breast cancer patients. In this review, the most promising candidates from the new generation of PI3K-pathway inhibitors is explored, presenting evidence from preclinical and early clinical research, as well as ongoing trials utilising these drugs in breast cancer cohorts. The problems hindering the development of drugs targeting the PI3K pathway are examined, which have created problems for their use as monotherapies. PI3K pathway inhibitor combinations therefore remains a dynamic research area, and their role in combination with immunotherapies and epigenetic therapies is also inspected.

Innovative Technologies Changing Cancer Treatment.

Conventional therapies for cancer such as chemotherapy and radiotherapy remain a mainstay in treatment, but in many cases a targeted approach is lacking, and patients can be vulnerable to drug resistance. In recent years, novel concepts have been emerging to improve the traditional therapeutic options in cancers with poor survival outcomes. New therapeutic strategies involving areas like energy metabolism and extracellular vesicles along with advances in immunotherapy and nanotechnology are driving the next generation of cancer treatments. The development of fields such as theranostics in nanomedicine is also opening new doors for targeted drug delivery and nano-imaging. Here we discuss the use of innovative technologies presented at the Irish Association for Cancer Research (IACR) Annual Meeting, highlighting examples of where new approaches may lead to promising new treatment options for a range of cancer types.

Cross-Talk between Cancer Cells and the Tumour Microenvironment: The Role of the 5-Lipoxygenase Pathway.

5-lipoxygenase is an enzyme responsible for the synthesis of a range of bioactive lipids signalling molecules known collectively as eicosanoids. 5-lipoxygenase metabolites such as 5-hydroxyeicosatetraenoic acid (5-HETE) and a number of leukotrienes are mostly derived from arachidonic acid and have been shown to be lipid mediators of inflammation in different pathological states including cancer. Upregulated 5-lipoxygenase expression and metabolite production is found in a number of cancer types and has been shown to be associated with increased tumorigenesis. 5-lipoxygenase activity is present in a number of diverse cell types of the immune system and connective tissue. In this review, we discuss potential routes through which cancer cells may utilise the 5-lipoxygenase pathway to interact with the tumour microenvironment during the development and progression of a tumour. Furthermore, immune-derived 5-lipoxygenase signalling can drive both pro- and anti-tumour effects depending on the immune cell subtype and an overview of evidence for these opposing effects is presented.

Anti-cancer effects of baicalein in non-small cell lung cancer in-vitro and in-vivo.

BACKGROUND: Baicalein is a widely used Chinese herbal medicine derived from Scutellaria baicalenesis, which has been traditionally used as anti-inflammatory and anti-cancer therapy. In this study we examined the anti-tumour pathways activated following baicalein treatment in non-small cell lung cancer (NSCLC), both in-vitro and in-vivo. METHODS: The effect of baicalein treatment on H-460 cells in-vitro was assessed using both BrdU assay (cell proliferation) and High Content Screening (multi-parameter apoptosis assay). A xenograft nude mouse model was subsequently established using these cells and the effect of baicalein on tumour growth and survival assessed in-vivo. Tumours were harvested from these mice and histological tissue analysis carried out. VEGF, 12-lipoxygenase and microvessel density (CD-31) were assessed by immunohistochemistry (IHC), while H and E staining was carried out to assess mitotic index. Gene expression profiling was carried out on corresponding RNA samples using Human Cancer Pathway Finder Arrays and qRT-PCR, with further gene expression analysis carried out using qRT-PCR. RESULTS: Baicalein significantly decreased lung cancer proliferation in H-460 cells in a dose dependent manner. At the functional level, a dose-dependent induction in apoptosis associated with decreased cellular f-actin content, an increase in nuclear condensation and an increase in mitochondrial mass potential was observed. Orthotopic treatment of experimental H-460 tumours in athymic nude mice with baicalein significantly (p < 0.05) reduced tumour growth and prolonged survival. Histological analysis of resulting tumour xenografts demonstrated reduced expression of both 12-lipoxygenase and VEGF proteins in baicalein-treated tumours, relative to untreated. A significant (p < 0.01) reduction in both mitotic index and micro-vessel density was observed following baicalein treatment. Gene expression profiling revealed a reduction (p < 0.01) in both VEGF and FGFR-2 following baicalein treatment, with a corresponding increase (p < 0.001) in RB-1. CONCLUSION: This study is the first to demonstrate efficacy of baicalein both in-vitro and in-vivo in NSCLC. These effects may be mediated in part through a reduction in both cell cycle progression and angiogenesis. At the molecular level, alterations in expression of VEGF, FGFR-2, and RB-1 have been implicated, suggesting a molecular mechanism underlying this in-vivo effect.

The mTOR pathway in obesity driven gastrointestinal cancers: Potential targets and clinical trials.

The mechanistic target of rapamycin (mTOR) is a crucial point of convergence between growth factor signalling, metabolism, nutrient status and cellular proliferation. The mTOR pathway is heavily implicated in the progression of many cancers and is emerging as an important driver of gastrointestinal (GI) malignancies. Due to its central role in adapting metabolism to environmental conditions, mTOR signalling is also believed to be critical in the development of obesity. Recent research has delineated that excessive nutrient intake can promote signalling through the mTOR pathway and possibly evoke changes to cellular metabolism that could accelerate obesity related cancers. Acting through its two effector complexes mTORC1 and mTORC2, mTOR dictates the transcription of genes important in glycolysis, lipogenesis, protein translation and synthesis and has recently been defined as a central mediator of the Warburg effect in cancer cells. Activation of the mTOR pathway is involved in both the pathogenesis of GI malignancies and development of resistance to conventional chemotherapy and radiotherapy. The use of mTOR inhibitors is a promising therapeutic option in many GI malignancies, with greatest clinical efficacy seen in combination regimens. Recent research has also provided insight into crosstalk between mTOR and other pathways which could potentially expand the list of therapeutic targets in the mTOR pathway. Here we review the available strategies for targeting the mTOR pathway in GI cancers. We discuss current clinical trials of both established and novel mTOR inhibitors, with particular focus on combinations of these drugs with conventional chemotherapy, radiotherapy and targeted therapies.

Vascular endothelial growth factor is an autocrine growth factor, signaling through neuropilin-1 in non-small cell lung cancer.

BACKGROUND: The VEGF pathway has become an important therapeutic target in lung cancer, where VEGF has long been established as a potent pro-angiogenic growth factor expressed by many types of tumors. While Bevacizumab (Avastin) has proven successful in increasing the objective tumor response rate and in prolonging progression and overall survival in patients with NSCLC, the survival benefit is however relatively short and the majority of patients eventually relapse. The current use of tyrosine kinase inhibitors alone and in combination with chemotherapy has been underwhelming, highlighting an urgent need for new targeted therapies. In this study, we examined the mechanisms of VEGF-mediated survival in NSCLC cells and the role of the Neuropilin receptors in this process. METHODS: NSCLC cells were screened for expression of VEGF and its receptors. The effects of recombinant VEGF and its blockade on lung tumor cell proliferation and cell cycle were examined. Phosphorylation of Akt and Erk1/2 proteins was examined by high content analysis and confocal microscopy. The effects of silencing VEGF on cell proliferation and survival signaling were also assessed. A Neuropilin-1 stable-transfected cell line was generated. Cell growth characteristics in addition to pAkt and pErk1/2 signaling were studied in response to VEGF and its blockade. Tumor growth studies were carried out in nude mice following subcutaneous injection of NP1 over-expressing cells. RESULTS: Inhibition of the VEGF pathway with anti-VEGF and anti-VEGFR-2 antibodies or siRNA to VEGF, NP1 and NP2 resulted in growth inhibition of NP1 positive tumor cell lines associated with down-regulation of PI3K and MAPK kinase signaling. Stable transfection of NP1 negative cells with NP1 induced proliferation in vitro, which was further enhanced by exogenous VEGF. In vivo, NP1 over-expressing cells significantly increased tumor growth in xenografts compared to controls. CONCLUSIONS: Our data demonstrate that VEGF is an autocrine growth factor in NSCLC signaling, at least in part, through NP1. Targeting this VEGF receptor may offer potential as a novel therapeutic approach and also support the evaluation of the role of NP1 as a biomarker predicting sensitivity or resistance to VEGF and VEGFR-targeted therapies in the clinical arena.

Excess visceral adiposity induces alterations in mitochondrial function and energy metabolism in esophageal adenocarcinoma.

BACKGROUND: Visceral obesity has a strong association with both the incidence and mortality of esophageal adenocarcinoma (EAC). Alterations in mitochondrial function and energy metabolism is an emerging hallmark of cancer, however, the potential role that obesity plays in driving these alterations in EAC is currently unknown. METHODS: Adipose conditioned media (ACM) was prepared from visceral adipose tissue taken from computed tomography-determined viscerally-obese and non-obese EAC patients. Mitochondrial function in EAC cell lines was assessed using fluorescent probes, mitochondrial gene expression was assessed using qPCR-based gene arrays and intracellular ATP levels were determined using a luminescence-based kit. Glycolysis and oxidative phosphophorylation was measured using Seahorse XF technology and metabolomic analysis was performed using 1H NMR. Expression of metabolic markers was assessed in EAC tumor biopsies by qPCR. RESULTS: ACM from obese EAC patients significantly increased mitochondrial mass and mitochondrial membrane potential in EAC cells, which was significantly associated with visceral fat area, and was coupled with a significant decrease in reactive oxygen species. This mitochondrial dysfunction was accompanied by altered expression of 19 mitochondrial-associated genes and significantly reduced intracellular ATP levels. ACM from obese EAC patients induced a metabolic shift to glycolysis in EAC cells, which was coupled with significantly increased sensitivity to the glycolytic inhibitor 2-deoxyglucose. Metabolomic profiling demonstrated an altered glycolysis and amino acid-related signature in ACM from obese patients. In EAC tumors, expression of the glycolytic marker PKM2 was significantly positively associated with obesity. CONCLUSION: This study demonstrates for the first time that ACM from viscerally-obese EAC patients elicits an altered metabolic profile and can drive mitochondrial dysfunction and altered energy metabolism in EAC cells in vitro. In vivo, in EAC patient tumors, expression of the glycolytic enzyme PKM2 is positively associated with obesity.

Thromboxane synthase expression and correlation with VEGF and angiogenesis in non-small cell lung cancer.

BACKGROUND: Thromboxane synthase (TXS) metabolizes prostaglandin H2 into thromboxanes, which are biologically active on cancer cells. TXS over-expression has been reported in a range of cancers, and associated with angiogenesis and poor outcome. TXS has been identified as a potential therapeutic target in NSCLC. This study examines a link between TXS expression, angiogenesis, and survival in NSCLC. METHODS: TXS and VEGF metabolite levels were measured in NSCLC serum samples (n=46) by EIA. TXB2 levels were correlated with VEGF. A 204-patient TMA was stained for TXS, VEGF, and CD-31 expression. Expression was correlated with a range of clinical parameters, including overall survival. TXS expression was correlated with VEGF and CD-31. Stable TXS clones were generated and the effect of overexpression on tumor growth and angiogenesis markers was examined in-vitro and in-vivo (xenograft mouse model). RESULTS: Serum TXB2 levels were correlated with VEGF (p<0.05). TXS and VEGF were expressed to a varying degree in NSCLC tissue. TXS was associated with VEGF (p<0.0001) and microvessel density (CD-31; p<0.05). TXS and VEGF expression levels were higher in adenocarcinoma (p<0.0001) and female patients (p<0.05). Stable overexpression of TXS increased VEGF secretion in-vitro. While no significant association with patient survival was observed for either TXS or VEGF in our patient cohort, TXS overexpression significantly (p<0.05) increased tumor growth in-vivo. TXS overexpression was also associated with higher levels of VEGF, microvessel density, and reduced apoptosis in xenograft tumors. CONCLUSION: TXS promotes tumor growth in-vivo in NSCLC, an effect which is at least partly mediated through increased tumor angiogenesis.

Expression of neuroepithelial transforming gene 1 is enhanced in oesophageal cancer and mediates an invasive tumour cell phenotype.

INTRODUCTION: Neuroepithelial Transforming Gene 1 (NET1) is a well characterised oncoprotein and a proven marker of an aggressive phenotype in a number of cancers, including gastric adenocarcinoma. We aimed to investigate whether NET1 plays a functional role in oesophageal cancer (OAC) and its pre-malignant phenotype Barrett's oesophagus. METHODS: Baseline NET1 mRNA levels were determined by qPCR across a panel of six cell lines, including normal oesophageal, Barrett's and OAC derived cells. Quantification of NET1 protein in OAC cells was performed using Western blot and immunofluorescence. NET1 expression was modulated by treating with lysophosphatidic acid (LPA) and NET1-specific siRNA. The functional effects of NET1 knockdown were assessed in vitro using proliferation, migration and invasion assays. RESULTS: NET1 expression was increased in Barrett's and in OAC-derived cells in comparison to normal oesophageal cells. The highest expression was observed in OE33 a Barrett's-related OAC cell line. NET1 protein and mRNA expression was enhanced by LPA treatment in OAC and furthermore LPA treatment caused increased proliferation, migration and invasion in a NET1-dependent manner. NET1 knockdown resulted in reduced OAC cell proliferation and invasion. CONCLUSIONS: As found in other malignancies, NET1 expression is elevated in OAC and its pre-malignant phenotype, Barrett's oesophagus. NET1 promotes OAC cell invasion and proliferation and it mediates LPA-induced OAC cell migration.

Establishing computed tomography-defined visceral fat area thresholds for use in obesity-related cancer research.

Excess visceral adiposity is associated with increased gastrointestinal cancer risk. Evidence suggests that the systemic inflammation and dysmetabolism observed in visceral obesity underpins this association. Along with magnetic resonance imaging, computed tomography is a gold standard for abdominal fat quantification and is routinely available for gastrointestinal cancer research. However, no gender-specific cutoff values are currently available for classifying visceral obesity in white populations. Using the metabolic syndrome (MetSyn) as an indicator of obesity-associated dysmetabolism, this study aimed to establish pathologically relevant, gender-specific cut-off values for use in obesity-associated cancer research. Total, visceral and subcutaneous fat areas were calculated between the L3 and L4 invertebral space from computed tomography scans in a cohort of 170 males and 66 females undergoing gastrointestinal resection. Receiver operating characteristics analysis was used to determine cut-off values for total, visceral and subcutaneous fat areas associated with MetSyn. Linear regression was used to correlate these values with waist circumference. Visceral fat area (VFA) strongly correlated with the presence of MetSyn (P < .0001). The cut-off value for VFA associated with the presence of MetSyn was 163.8 cm(2) in males (83.6% sensitivity, 62.5% specificity) and 80.1 cm(2) for females (96% sensitivity, 73.2% specificity). The waist circumference corresponding to these VFA values was 96.1 cm in males and 83.2 cm in females. This study is the first to generate gender-specific and pathologically relevant cut-off values for VFA in patients with gastrointestinal cancer. In the field of obesity-associated research, this new anthropometric measure is of paramount importance for determining the accurate pathological obesity status of cancer patients.

MMP9 expression in oesophageal adenocarcinoma is upregulated with visceral obesity and is associated with poor tumour differentiation.

Overweight and obesity is linked to increased incidence and mortality of many cancer types. Of all cancers, oesophageal adenocarcinoma (OAC) displays one of the strongest epidemiological links with obesity, accounting for up to 40% of cases, but molecular pathways driving this association remain largely unknown. This study aimed to elucidate mechanisms underpinning the association of obesity and cancer, and to determine if visceral obesity is associated with aggressive tumour biology in OAC. Following co-culture with visceral adipose tissue explants, expression of genes involved in tumour cell invasion and metastasis (matrix metalloproteinase (MMP)2 and MMP9) were upregulated between 10-fold (MMP2) and 5000-fold (MMP9), and expression of tumour suppressor p53 was downregulated 2-fold in OAC cell lines. Western blotting confirmed these results at the protein level, while zymographic analysis detected increased activity of MMPs in OAC cell lines following co-culture with adipose tissue explants. When OAC cell lines were cultured with adipose tissue conditioned media (ACM) from visceral adipose tissue, increased proliferative, migratory and invasive capacity of tumour cells was observed. In OAC patient tumour biopsies, elevated gene expression of MMP9 was associated with visceral obesity, measured by visceral fat area, while increased gene expression of MMP9 and decreased gene expression of tumour suppressor p53 was associated with poor tumour differentiation. These novel data highlight an important role for visceral obesity in upregulation of pro-tumour pathways contributing to aggressive tumour biology, and may ultimately lead to development of stratified treatment for viscerally obese OAC patients.

Elevated Tumor Expression of PAI-1 and SNAI2 in Obese Esophageal Adenocarcinoma Patients and Impact on Prognosis.

OBJECTIVES: Obesity is linked to increased mortality from many cancer types, and esophageal adenocarcinoma (EAC) displays one of the strongest epidemiological associations. The aims of this study are to dissect molecular pathways linking obesity with EAC and to determine if obesity is linked to increased aggressiveness of this disease. METHODS: Affymetrix microarrays identified altered signaling pathways in an EAC cell line following coculture with visceral adipose tissue or isolated adipocytes from viscerally obese EAC patients (n=6). Differentially expressed genes were subsequently investigated in patient tumor biopsies by quantitative reverse transcriptase PCR and examined with respect to obesity status, tumor biology, and patient survival. RESULTS: Visceral adipose tissue induced expression of genes involved in epithelial mesenchymal transition (EMT), plasminogen activator inhibitor (PAI)-1, and transcription factor SNAI2, in an EAC cell line. In EAC patient tumor biopsies from obese patients, we noted elevated expression of these genes, together with reduced expression of epithelial marker E-cadherin. SNAI2 was associated with EAC prognosis. CONCLUSIONS: Expression of EMT genes, PAI-1 and SNAI2, was elevated in tumors of obese EAC patients, and SNAI2 was associated with poor survival. Genes deregulated in obesity and associated with prognosis may represent potential targets for treatment stratification of obese EAC patients.

The SGBS cell strain as a model for the in vitro study of obesity and cancer.

INTRODUCTION: The murine adipocyte cell line 3T3-L1 is well characterised and used widely, while the human pre-adipocyte cell strain, Simpson-Golabi-Behmel Syndrome (SGBS), requires validation for use in human studies. Obesity is currently estimated to account for up to 41 % of the worldwide cancer burden. A human in vitro model system is required to elucidate the molecular mechanisms for this poorly understood association. This work investigates the relevance of the SGBS cell strain for obesity and cancer research in humans. MATERIALS AND METHODS: Pre-adipocyte 3T3-L1 and SGBS were differentiated according to standard protocols. Morphology was assessed by Oil Red O staining. Adipocyte-specific gene expression was measured by qPCR and biochemical function was assessed by glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity. Differential gene expression in oesophageal adenocarcinoma cell line OE33 following co-culture with SGBS or primary omental human adipocytes was investigated using Human Cancer Profiler qPCR arrays. RESULTS: During the process of differentiation, SGBS expressed higher levels of adipocyte-specific transcripts and fully differentiated SGBS expressed more similar morphology, transcript levels and biochemical function to primary omental adipocytes, relative to 3T3-L1. Co-culture with SGBS or primary omental adipocytes induced differential expression of genes involved in adhesion (ITGB3), angiogenesis (IGF1, TEK, TNF, VEGFA), apoptosis (GZMA, TERT) and invasion and metastasis (MMP9, TIMP3) in OE33 tumour cells. CONCLUSIONS: Comparable adipocyte-specific gene expression, biochemical function and a shared induced gene signature in co-cultured OE33 cells indicate that SGBS is a relevant in vitro model for obesity and cancer research in humans.

MicroRNA-31 modulates tumour sensitivity to radiation in oesophageal adenocarcinoma.

Chemoradiation therapy (CRT) prior to surgery is increasingly the standard of care for locally advanced oesophageal cancer. Radiation therapy is important for local tumour control; however, tumour resistance to radiation is a substantial clinical problem. The mechanism(s) of radioresistance are still poorly understood, however, mounting evidence supports a role for microRNA (miRNA) in modulating key cellular pathways mediating response to radiation. Global miRNA profiling of an established isogenic model of radioresistance in oesophageal adenocarcinoma demonstrated a significant downregulation of miR-31 in radioresistant cells, both basally and in response to radiation. Ectopic re-expression of miR-31 significantly re-sensitised radioresistant cells to radiation. miR-31 was demonstrated to alter the expression of 13 genes involved in DNA repair, which is a critical cellular defence against radiation-induced DNA damage. In oesophageal tumours, miR-31 expression was significantly reduced in patients demonstrating poor histomorphologic response to neoadjuvant CRT, whilst expression of the miR-31-regulated DNA repair genes was significantly increased. Our data suggest a possible mechanism for resistance to CRT, potentially via enhanced DNA repair. This study demonstrates, for the first time, a role for miR-31 in modulating radioresistance and highlights the need for further study investigating the potential role of miR-31 as both a predictive marker of response and a novel therapeutic agent with which to enhance the efficacy of radiation therapy.

COX-derived prostanoid pathways in gastrointestinal cancer development and progression: novel targets for prevention and intervention.

Arachidonic acid metabolism through cyclooxygenase (COX) pathways leads to the generation of biologically active eicosanoids. Eicosanoid expression levels vary during development and progression of gastrointestinal (GI) malignancies. COX-2 is the major COX-isoform responsible for G.I. cancer development/progression. COX-2 expression increases during progression from a normal to cancerous state. Evidence from observational studies has demonstrated that chronic NSAID use reduces the risk of cancer development, while both incidence and risk of death due to G.I. cancers were significantly reduced by daily aspirin intake. A number of randomized controlled trials (APC trial, Prevention of Sporadic Adenomatous Polyps trial, APPROVe trial) have also shown a significant protective effect in patients receiving selective COX-2 inhibitors. However, chronic use of selective COX-2 inhibitors at high doses was associated with increased cardiovascular risk, while NSAIDs have also been associated with increased risk. More recently, downstream effectors of COX-signaling have been investigated in cancer development/progression. PGE(2), which binds to both EP and PPAR receptors, is the major prostanoid implicated in the carcinogenesis of G.I. cancers. The role of TXA(2) in G.I. cancers has also been examined, although further studies are required to uncover its role in carcinogenesis. Other prostanoids investigated include PGD(2) and its metabolite 15d-PGJ2, PGF(1α) and PGI(2). Targeting these prostanoids in G.I. cancers has the promise of avoiding cardiovascular toxicity associated with chronic selective COX-2 inhibition, while maintaining anti-tumor reactivity. A progressive sequence from normal to pre-malignant to a malignant state has been identified in G.I. cancers. In this review, we will discuss the role of the COX-derived prostanoids in G.I. cancer development and progression. Targeting these downstream prostanoids for chemoprevention and/or treatment of G.I. cancers will also be discussed. Finally, we will highlight the latest pre-clinical technologies as well as avenues for future investigation in this highly topical research field.

IGF-1 and its receptor in esophageal cancer: association with adenocarcinoma and visceral obesity.

OBJECTIVES: The insulin-like growth factor (IGF) pathway and visceral obesity have been independently linked with esophageal cancer. This study aimed to delineate the differential and interlinked role of visceral obesity and the IGF-1 system in esophageal adenocarcinoma and esophageal squamous-cell carcinoma (SCC). METHODS: IGF-1 receptor (IGF-1R) mRNA and protein were examined in esophageal SCC (KYSE 410, OE21) and esophageal adenocarcinoma (OE19, OE33) cell lines by western blotting. Tumor cell proliferation in response to IGF-1 was assessed by bromodeoxyuridine incorporation assay. In esophageal tumor sections, expression of IGF-1R and CD68(+) cell numbers were assessed by immunohistochemistry. IGF-1 was measured in serum from esophageal cancer patients, Barrett's esophagus patients, and healthy controls by enzyme-linked immunosorbent assay. RESULTS: Higher IGF-1R protein expressions were observed in SCC cells compared with esophageal adenocarcinoma cells however only adenocarcinoma cell lines significantly increased proliferation in response to IGF-1 (P<0.01). Serum IGF-1 levels were highest in esophageal adenocarcinoma patients (P<0.01) and higher in viscerally obese vs. nonobese (P<0.05) patients. In resected esophageal cancer, increased expression of IGF-1R was observed in the tumor and invasive edge compared with tumor-associated stroma (P<0.05), which coincided with increased CD68(+) cells in stromal tissue surrounding invasive tumor edge (P<0.01). CONCLUSIONS: This novel study examined the differential role of the IGF system in esophageal adenocarcinoma and SCC, and its association with visceral obesity. These results indicate that the IGF-1 axis has a key role in malignant progression of esophageal cancer, and represents a plausible mechanism through which visceral obesity impacts on esophageal adenocarcinoma risk and tumor biology.

Eicosanoid signalling pathways in the development and progression of colorectal cancer: novel approaches for prevention/intervention.

Arachidonic acid metabolism through cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P-450 epoxygenase (EPOX) pathways leads to the generation of biologically active eicosanoids, including prostanoids, leukotrienes, hydroxyeicosatetraenoic acid, epoxyeicosatrienoic acid and hydroperoxyeicosatetraenoic acids. Eicosanoid expression levels vary during tumor development and progression of a range of malignancies, including colorectal cancer. The actions of these autocoids are also directly influenced by diet, as demonstrated by recent evidence for omega-3 fatty acids in colorectal cancer (CRC) prevention and/or treatment. Eicosanoids regulate CRC development and progression, while inhibition of these pathways has generally been shown to inhibit tumor growth/progression. A progressive sequence of colorectal cancer development has been identified, ranging from normal colon, to colitis, dysplasia, and carcinoma. While both COX and LOX inhibition are both promising candidates for colorectal cancer prevention and/or treatment, there is an urgent need to understand the mechanisms through which these signalling pathways mediate their effects on tumorigenesis. This will allow identification of safer, more effective strategies for colorectal cancer prevention and/or treatment. In particular, binding to/signalling through prostanoid receptors have recently been the subject of considerable interest in this area. In this review, we discuss the role of the eicosanoid signalling pathways in the development and progression of colorectal cancer. We discuss the effects of the eicosanoids on tumor cell proliferation, their roles in cell death induction, effects on angiogenesis, migration, invasion and their regulation of the immune response. Signal transduction pathways involved in these processes are also discussed. Finally, novel approaches targeting these arachidonic acid-derived eicosanoids (using pharmacological or natural agents) for chemoprevention and/or treatment of colorectal cancer are outlined.

Influence of the metabolic syndrome on leptin and leptin receptor in breast cancer.

Obesity and its associated metabolic syndrome (MetS) are recognized risk factors for breast cancer. The molecular basis for this association remains largely unknown. Adipokines, in particular leptin and adiponectin, are thought to form part of the mechanism linking obesity with cancer through their altered expression/production either systemically (endocrine pathway) or locally (paracrine/autocrine pathway). Using quantitative PCR, mRNA expression of adiponectin (AdipoQ) and leptin (Ob) in mammary adipose tissue (MAT), intratumoral leptin and associated ligand receptors (ObR, AdipoR1, and AdipoR2) was examined in 77 patients with complete anthropomorphic and serological data. Expression of Ob in MAT, and ObR in matched tumor tissue was significantly higher in patients with MetS compared to obese only or normal weight cancer patients (P < 0.005). There was no difference in intratumoral leptin adiponectin or its ligand receptors in the same groups. Individual features of MetS correlated with Ob and ObR expression, but not obesity markers (BMI, waist circumference). mRNA expression of leptin (Ob) and ObR, in adipose tissue and matched tumor samples, respectively, appear to be associated with obesity status in breast cancer. Increasing insulin resistance is a predominant feature of this higher Ob/ObR expression observed. These novel data indicate that the MetS may be an amenable risk factor for breast cancer.